Abstract RNA interference (RNAi) is a powerful gene silencing technology, widely used in analyses of reverse genetics, development of therapeutic strategies and generation of biotechnological products. Here we present a free software tool for the rational design of RNAi effectors, named siRNA and shRNA designer (SSD). SSD incorporates our previously developed software Strand Analysis to construct template DNAs amenable for the large scale production of mono-, bi- and trivalent multimeric shRNAs, via in vitro rolling circle transcription. We tested SSD by creating a trivalent multimeric shRNA against the vitellogenin gene of Apis mellifera. RT-qPCR analysis revealed that our molecule promoted a decrease in more than 50% of the target mRNA, in a dose-dependent manner, when compared to the control group. Thus, SSD software allows the easy design of multimeric shRNAs, for single or multiple simultaneous knockdowns, which is especially interesting for studies involving large amounts of double-stranded molecules.

O objetivo deste estudo foi verificar o pH preferencial de jundiás Rhamdia quelen aclimatados em diferentes pH. Os jundiás foram aclimatados por uma semana em pH 4,2±0,1; 5,2±0,1; 6,3±0,1; 7,2±0,1; 8,0±0,1 e 9,0±0,1 e, após esse período, transferidos para um tubo de polietileno com pH variando entre 3,5 e 10. A posição dos exemplares no gradiente de pH foi observada 1, 6 e 12 horas após a transferência. Os resultados indicam que a aclimatação em diferentes pH não altera o pH preferencial dos peixes (pH 7.0-7.6), ocorrendo apenas uma variação transitória em torno de 6 horas após a transferência. Este pH preferencial coincide com o pH indicado na literatura como o melhor para o crescimento desta espécie.

The aim of this study was to investigate the preferred pH in silver catfish Rhamdia quelen acclimated to different pH. Fish were acclimated for one week at pH 4.2±0.1, 5.2±0.1, 6.3±0.1, 7.2±0.1, 8.0±0.1, and 9.0±0.1 and after this period, transferred to a polyethylene tube with a pH gradient from 3.5 to 10.0. The position of the fish in the pH gradient was observed 1, 6 and 12 hours after transference. Results indicated that acclimation to different pH did not change pH preference of silver catfish (pH 7.0-7.6), occurring only a transitory variation around 6 hours after transference. This pH preference coincides with the best pH indicated in the literature for growth of this species.